Tectonic Hazards

Front

Which of the following is a hazard associated with BOTH volcanic eruptions and earthquakes? Tephra, Pyroclastic Flows, Tsunamis, Lahars

Back

Tsunamis

Answer explanation

Tsunamis are a series of ocean waves caused by undersea earthquakes, volcanic eruptions and landslides.

Front

The closer it is to the epicentre, the greater the earthquake intensity.

Back

True

Answer explanation

Notice that the earthquake intensity tapers off with increasing distance from the earthquake's epicentre, and it is generally felt within Mexico. E.g. 2017 Earthquake in Chiapas, Mexico

Front

What causes the tectonic plates to move?

Back

Convection currents

Front

Do volcanoes occur at conservative plate boundaries?

Back

No, volcanoes do not occur at conservative plate boundaries.

Front

What is the name given to a volcano which does not occur on a plate boundary?

Back

Hotspot

Front

Possible impacts of ground shaking caused by Earthquakes

Back

Disruption of essential services, Destruction of properties and infrastructure, Injuries and fatalities

Front

Soil liquefaction

Back

When violent ground shaking causes saturated wet soil to transform into a thick fluid.

Answer explanation

• Triggered by shaking or vibration, especially during earthquakes.

• Requires water-saturated soil.

• Can cause severe ground failure, leading to buildings tilting, sinking, or collapsing.

Front

What happens to tsunami waves as they approach the coast?

Back

They slow down and increase in height.

Answer explanation

On approaching the coast, greater friction with the shallower seabed slows the

waves down. The waves get closer together and increase in height. Waves can reach up to a

height of 15m or more, travel at a speed of 30 - 50km/h and devastate shorelines

the waves hit.

Front

A ___________ flow is a hot cloud of gas, ash, and rocks travelling down the slopes of a volcano.

Back

pyroclastic

Answer explanation

A pyroclastic flow is a hot cloud of gas, ash, and rocks travelling down the slopes of a volcano at great speeds of more than 200km/hour. With temperatures of up to 700 °C, it is perhaps the most devastating of all volcanic hazards.

Front

Which of the following is NOT a cause of lahars?

• When pyroclastic flow melt snow and ice
• After an intense rainfall
• When volcanic eruption hits the oceans
• When lakes on the volcano collapse

Back

When volcanic eruption hits the oceans.

Answer explanation

Lahars (volcanic mudflows or debris flows) are volcanic in origin and involve water mixing with volcanic ash, rock, and debris.